1. Field of the Invention
The present invention relates to a diode which is one of devices constituting a power module, and more particularly, to a semiconductor device that can improve a withstand voltage while reducing reverse recovery loss and suppressing a surge voltage.
2. Background Art
Reverse recovery loss, which is an important characteristic of diodes, has relevance to the lifetime of a carrier. When, for example, the number of crystal defects is increased to shorten the lifetime, the reverse recovery loss decreases. Thus, a technique of introducing crystal defects through irradiation of an electron beam and controlling the lifetime of the entire device is used to obtain a diode which has arbitrary reverse recovery loss.
Furthermore, a diode is also proposed in which crystal defects are partially introduced between an N-type drift layer and a P-type anode layer and a short lifetime layer whose carrier has a short lifetime is provided (e.g., see Japanese Patent Laid-Open No. 2003-249662).